This application is a 371 of a PCT/US99/7613 filed Jun. 7, 1999.
Along with surgery and radiotherapy, chemotherapy continues to be an effective therapy for many cancers. In fact, several types of cancer are now considered to be curable by chemotherapy and include Hodgkin""s disease, large cell lymphoma, acute lymphocytic leukemia, testicular cancer and early stage breast cancer. Other cancers such as ovarian cancer, small cell lung and advanced breast cancer, while not yet curable, are exhibiting positive response to combination chemotherapy.
One of the most important unsolved problems in cancer treatment is drug resistance. After selection for resistance to a single cytotoxic drug, cells may become cross resistant to a whole range of drugs with different structures and cellular targets, e.g., alkylating agents, antimetabolites, hormones, platinum-containing drugs, and natural products. This phenomenon is known as multidrug resistance (MDR). In some types of cells, this resistance is inherent, while in others, such as small cell lung cancer, it is usually acquired.
Such resistance is known to be multifactorial and is conferred by at least two proteins: the 170 kDa P-glycoprotein (MDR1) and the more recently identified 190 kDa multidrug resistance protein (MRP1). Although both MDR1 and MRP1 belong to the ATP-binding cassette superfamily of transport proteins, they are structurally very different molecules and share less than 15% amino acid homology. Despite the structural divergence between the two proteins, by 1994 there were no known consistent differences in the resistance patterns of MDR1 and MRP1 cell lines. However, the association, or lack thereof, of MRP1 and resistance to particular oncolytics is known. See Cole, et. al., xe2x80x9cPharmacological Characterization of Multidrug Resistant MRP-transfected Human Tumor Cellsxe2x80x9d, Cancer Research, 54:5902-5910, 1994. Doxorubicin, daunorubicin, epirubicin, vincristine, and etoposide are substrates of MRP1, i.e., MRP1 can bind to these oncolytics and redistribute them away from their site of action, the nucleus, and out of the cell. Id. and Marquardt, D., and Center, M. S., Cancer Research, 52:3157, 1992.
Doxorubicin, daunorubicin, and epirubicin are members of the anthracycline class of oncolytics. They are isolates of various strains of Streptomyces and act by inhibiting nucleic acid synthesis. These agents are useful in treating neoplasms of the bone, ovaries, bladder, thyroid, and especially the breast. They are also useful in the treatment of acute lymphoblastic and myeloblastic leukemia, Wilm""s tumor, neuroblastoma, soft tissue sarcoma, Hodgkin""s and non-Hodgkin""s lymphomas, and bronchogenic carcinoma.
Vincristine, a member of the vinca alkaloid class of oncolytics, is an isolate of a common flowering herb, the periwinkle plant (Vinca rosea Linn). The mechanism of action of vincristine is still under investigation but has been related to the inhibition of microtubule formation in the mitotic spindle. Vincristine is useful in the treatment of acute leukemia, Hodgkin""s disease, non-Hodgkin""s malignant lymphomas, rhabdomyosarcoma, neuroblastoma, and Wilm""s tumor.
Etoposide, a member of the epipodophyllotoxin class of oncolytics, is a semisynthetic derivative of podophyllotoxin. Etoposide acts as a topoisomerase inhibitor and is useful in the therapy of neoplasms of the testis, and lung.
It is presently unknown what determines whether a cell line will acquire resistance via a MDR1 or MRP1 mechanism. Due to the tissue specificity of these transporters and/or in the case where one mechanism predominates or is exclusive, it would be useful to have a selective inhibitor of that one over the other. Furthermore, when administering a drug or drugs that are substrates of either protein, it would be particularly advantageous to coadminister an agent that is a selective inhibitor of that protein. It is, therefore, desirable to provide compounds which are selective inhibitors of MDR1 or MRP1.
The present invention relates to a compound of formula I: 
where:
R is (CH2)mxe2x80x2CHR1NHR2, O(CH2)2NHR2, (CH2)mxe2x80x2COR3, NHR2, and (CH2)mxe2x80x2CHR1NR4R5;
Rxe2x80x2 is hydrogen, hydroxy, or O(C1-C6 alkyl optionally substituted with phenyl or C3-C7 cycloalkyl);
m and m1 are independently at each occurrence 0, 1, or 2;
Rxe2x80x2 is independently at each occurrence hydrogen or C1-C6 alkyl;
R2 is hydrogen, COR6, CH2Rxe2x80x2, SO2R7, or a moiety of the formula 
R3 is hydrogen, hydroxy, C1-C6 alkoxy, an amino ester, an amino acid, or NR4R5;
R4 is hydrogen or C1-C6 alkyl;
R5 is hydrogen, C1-C6 alkyl, C6-C10 bicycloalkyl, CH2CH(CH3)phenyl, CH(CH3)CH2CO2R1, aryl, substituted aryl, (CH2)nCHR8NHC(O)OC(CH3)3, (CH2)nNH2, (CH2)2NHCOR6, (CH2)2OH, (CH2)q-heterocycle, (CH2)q-substituted heterocycle, or R4 and R5 combine to form a pyrrolidin-1-yl, piperidin-1-yl, hexamethyleneimin-1-yl, or morpholin-4-yl ring;
n is 1, 2, 3, or 4;
q is 0, 1, 2, or 3;
R6 is C1-C6 alkyl, substituted C3-C6 cycloalkyl, aryl, substituted aryl, tert-butoxy, (CH2)q-heterocycle, (CH2)q-substituted heterocycle, (CH2)nS(O)rR1, C(CH3)2CH2N(R1)2, (CH2)nCHR8NHC(O)OC(CH3)3, (CH2) nNCHR8NH2, (CH2)2NH-aryl, or NHR7;
R6xe2x80x2 is C1-C6 alkyl, substituted C3-C6 cycloalkyl, aryl, substituted aryl, (CH2)q-heterocycle, (CH2)q-substituted heterocycle, (CH2)nS(O)rR1, C(CH3)C2CH2N(R1)2, (CH2)nCHR8NHxe2x80x94C(O)OC(CH3)3, (CH2)nCHR8NH2, or (CH2)2NH-aryl;
r is 0, 1, or 2;
R7 is C1-C6 alkyl, phenyl, or substituted phenyl; and
R8 is hydrogen or CO2R1; or a pharmaceutical salt or solvate thereof.
The present invention further relates to a method of inhibiting MRP1 in a mammal which comprises administering to a mammal in need thereof an effective amount of a compound of formula I, or a pharmaceutical salt or solvate thereof.
In another embodiment, the present invention relates to a method of inhibiting a resistant neoplasm, or a neoplasm susceptible to resistance in a mammal which comprises administering to a mammal in need thereof an effective amount of a compound of formula I, or a pharmaceutical salt or solvate thereof, in combination with an effective amount of an oncolytic agent.
The present invention also relates to a pharmaceutical formulation comprising a compound of formula I, or a pharmaceutical salt or solvate thereof, in combination with one or more oncolytics, pharmaceutical carriers, diluents, or excipients therefor.
The current invention concerns the discovery that a select group of compounds, those of formula I, are selective inhibitors of multidrug resistant protein (MRP1) and are thus useful in treating MRP1 conferred multidrug resistance (MDR) in a resistant neoplasm and a neoplasm susceptible to resistance.
The terms xe2x80x9cinhibitxe2x80x9d as it relates to MRP1 and xe2x80x9cinhibiting MRP1xe2x80x9d refer to prohibiting, alleviating, ameliorating, halting, restraining, slowing or reversing the progression of, or reducing MRP1""s ability to redistribute an oncolytic away from the oncolytic""s site of action, most often the neoplasm""s nucleus, and out of the cell.
As used herein, the term xe2x80x9ceffective amount of a compound of formula Ixe2x80x9d refers to an amount of a compound of the present invention which is capable of inhibiting MRP1. The term xe2x80x9ceffective amount of an oncolyticxe2x80x9d refers to an amount of oncolytic capable of inhibiting a neoplasm, resistant or otherwise.
The term xe2x80x9cinhibiting a resistant neoplasm, or a neoplasm susceptible to resistancexe2x80x9d refers to prohibiting, halting, restraining, slowing or reversing the progression of, reducing the growth of, or killing resistant neoplasms and/or neoplasms susceptible to resistance.
The term xe2x80x9cresistant neoplasmxe2x80x9d refers to a neoplasm which is resistant to chemotherapy where that resistance is conferred in part, or in total, by MRP1. Such neoplasms include, but are not limited to, neoplasms of the bladder, bone, breast, lung(small-cell), testis, and thyroid and also includes more particular types of cancer such as, but not limited to, acute lymphoblastic and myeloblastic leukemia, Wilm""s tumor, neuroblastoma, soft tissue sarcoma, Hodgkin""s and non-Hodgkin""s lymphomas, and bronchogenic carcinoma.
A neoplasm which is xe2x80x9csusceptible to resistancexe2x80x9d is a neoplasm where resistance is not inherent nor currently present but can be conferred by MRP1 after chemotherapy begins. Thus, the methods of this invention encompass a prophylactic and therapeutic administration of a compound of formula I.
The term xe2x80x9cchemotherapyxe2x80x9d refers to the use of one or more oncolytics where at least one oncolytic is a substrate of MRP1. A xe2x80x9csubstrate of MRP1xe2x80x9d is an oncolytic that binds to MRP1 and is redistributed away from the oncolytics site of action, (the neoplasm""s nucleus) and out of the cell, thus, rendering the therapy less effective.
The terms xe2x80x9ctreatxe2x80x9d or xe2x80x9ctreatingxe2x80x9d bear their usual meaning which includes preventing, prohibiting, alleviating, ameliorating, halting, restraining, slowing or reversing the progression, or reducing the severity of MRP1 derived drug resistance in a multidrug resistant tumor.
In the general formulae of the present document, the general chemical terms have their usual meanings. For example, the term xe2x80x9cC1-C4 alkylxe2x80x9d refers to methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, cyclobutyl, s-butyl, and t-butyl. The term xe2x80x9cC1-C6 alkylxe2x80x9d refers to a monovalent, straight, branched, or cyclic saturated hydrocarbon containing from 1 to 6 carbon atoms and includes C1-C4 alkyl groups in addition, C1-C6 alkyl also includes, but is not limited to, cyclopentyl, pentyl, hexyl, cyclohexyl, and the like. The term xe2x80x9cC3-C6 cycloalkylxe2x80x9d refers to cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The term xe2x80x9cC5-C7 cycloalkylxe2x80x9d refers to cyclopentyl, cyclohexyl, and cycloheptyl. The term xe2x80x9cC6-C10 bicycloalkylxe2x80x9d refers to bicyclo-[2.1.1]hexanyl, [2.2.1]heptanyl, [3.2.1]octanyl, [2.2.2]octanyl, [3.2.2]nonanyl, [3.3.1]nonanyl, [3.3.2]decanyl, and [4.3.1]decanyl ring system where the ring is connected to the parent molecular moiety at any point available for substitution on the ring.
The terms xe2x80x9cC1-C4 alkoxyxe2x80x9d and xe2x80x9cC1-C6 alkoxyxe2x80x9d refer to moieties of the formula O-(C1-C4 alkyl) and O-(C1-C6 alkyl) respectively.
The term xe2x80x9csubstituted C3-C6 cycloalkylxe2x80x9d refers to a C3-C6 cycloalkyl substituted once with a phenyl, substituted phenyl, or CO2R1 group.
The term xe2x80x9chaloxe2x80x9d or xe2x80x9chalidexe2x80x9d refers to fluoro, chloro, bromo, and iodo.
The term xe2x80x9carylxe2x80x9d refers to phenyl, benzyl, and napthyl.
The terms xe2x80x9csubstituted arylxe2x80x9d refers to a phenyl, benzyl, and napthyl group respectively substituted from 1 to 5 times independently with C1-C6 alkyl, halo, hydroxy, trifluoromethyl, N(R1)2, SO2N(R1)2, NHxe2x80x94Pg, C1-C6 alkoxy, benzyloxy, CO2R1, C5-C7 cycloalkyl, trifluoromethoxy, or nitro.
The term xe2x80x9cheterocyclexe2x80x9d refers to a monovalent, saturated, unsaturated, or aromatic mono cyclic or fused ring system of 5 to 7 or 8 to 10 total atoms respectively containing from 1 to 3 heteroatoms selected independently from oxygen, sulfur, and nitrogen.
The term xe2x80x9csubstituted heterocyclexe2x80x9d refers to a heterocycle ring substituted 1 or 2 times independently with a C1-C6 alkyl, halo, benzyl, phenyl, trifluoromethyl, or an oxo group.
The term xe2x80x9camino acidxe2x80x9d as used in this specification refers to an N-terminally connected glycine, valine, methionine, phenylalanine, tryptophane, proline, aspartic acid, and glutamic acid.
The term xe2x80x9camino esterxe2x80x9d as used in this specification refers to an amino acid where the carboxy group(s) of each (aspartic acid and glutamic acid each have two while the rest contain only one carboxy group) are substituted with a C1-C6 alkyl group. That is, the alkyl group when taken together with the carboxy group form a C1-C6 alkyl ester.
The term xe2x80x9cprotecting groupxe2x80x9d refers to an amino protecting group or a hydroxy protecting group. The species of protecting group will be evident from whether the xe2x80x9cPgxe2x80x9d group is attached to a nitrogen atom (amino protecting group) or attached to an oxygen atom (hydroxy protecting group).
The term xe2x80x9camino protecting groupxe2x80x9d as used in this specification refers to a substituent(s) of the amino group commonly employed to block or protect the amino functionality while reacting other functional groups on the compound. Examples of such amino-protecting groups include the formyl group, the trityl group, the phthalimido group, the acetyl group, the trichloroacetyl group, the chloroacetyl, bromoacetyl, and iodoacetyl groups, urethane-type blocking groups such as benzyloxycarbonyl, 9-fluorenylmethoxycarbonyl (xe2x80x9cFMOCxe2x80x9d), and the like; and like amino protecting groups. The species of amino protecting group employed is not critical so long as the derivitized amino group is stable to the condition of subsequent reaction(s) on other positions of the molecule and can be removed at the appropriate point without disrupting the remainder of the molecule. Similar amino protecting groups used in the cephalosporin, penicillin, and peptide arts are also embraced by the above terms. Further examples of groups referred to by the above terms are described by T. W. Greene, Protective Groups in Organic Synthesisxe2x80x9d, John Wiley and Sons, New York, N.Y., 1991, Chapter 7 hereafter referred to as xe2x80x9cGreenexe2x80x9d. A preferred amino protecting group is t-butyloxycarbonyl.
The term xe2x80x9chydroxy protecting groupxe2x80x9d denotes a group understood by one skilled in the organic chemical arts of the type described in Chapter 2 of Greene. Representative hydroxy protecting groups include, for example, ether groups including methyl and substituted methyl ether groups such as methyl ether, methoxymethyl ether, methylthiomethyl ether, tert-buylthiomethyl ether, (phenyldimethylsilyl)methoxy-methyl ether, benzyloxymethyl ether, p-methoxybenzyloxy-methyl ether, and tert-butoxymethyl ether; substituted ethyl ether groups such as ethoxyethyl ether, 1-(2-chloroethoxy)-ethyl ether, 2,2,2-trichloroethoxymethyl ether, and 2-(trimethylsilyl)ethyl ether; isopropyl ether groups; phenyl and substituted phenyl ether groups such as phenyl ether, p-chlorophenyl ether, p-methoxyphenyl ether, and 2,4-dinitrophenyl ether; benzyl and substituted benzyl ether groups such as benzyl ether, p-methoxybenzyl ether, o-nitrobenzyl ether, and 2,6-dichlorbenzyl ether; and alkylsilyl ether groups such as trimethyl- triethyl- and triisopropylsilyl ethers, mixed alkylsilyl ether groups such as dimethylisopropylsilyl ether, and diethylisopropylsilyl ether; and ester protecting groups such as formate ester, benzylformate ester, mono- di- and trichloroacetate esters, phenoxyacetate ester, and p-chlorophenoxyacetate and the like. The species of hydroxy protecting group employed is not critical so long as the derivatized hydroxy group is stable to the conditions of subsequent reaction(s) on other positions of the intermediate molecule and can be selectively removed at the appropriate point without disrupting the remainder of the molecule including any other hydroxy protecting group(s).
The term xe2x80x9ccarbonyl activating groupxe2x80x9d refers to a substituent of a carbonyl that renders that carbonyl prone to nucleophilic addition. Suitable activating groups are those which have a net electron withdrawing effect on the carbonyl. Such groups include, but are not limited to, alkoxy, aryloxy, nitrogen containing aromatic heterocycles, or amino groups such as oxybenzotriazole, imidazolyl, nitrophenoxy, pentachlorophenoxy, N-oxysuccinimide, N,Nxe2x80x2-dicyclohexylisoure-O-yl, N-hydroxy-N-methoxyamino, and the like; acetates, formates, sulfonates such as methanesulfonate, ethanesulfonate, benzenesulfonate, or p-toluenylsulfonate, and the like; and halides especially chloride, bromide, or iodide.
In general, the term xe2x80x9cpharmaceuticalxe2x80x9d when used as an adjective means substantially non-toxic to living organisms. For example, the term xe2x80x9cpharmaceutical saltxe2x80x9d as used herein, refers to salts of the compounds of formula I which are substantially non-toxic to living organisms. See, e.g., Berge, S. M, Bighley, L. D., and Monkhouse, D. C., xe2x80x9cPharmaceutical galtsxe2x80x9d, J. Pharm. Sci., 66:1, 1977. Typical pharmaceutical salts include those salts prepared by reaction of the compounds of formula I with an inorganic or organic acid or base. Such salts are known as acid addition or base addition salts respectively. These pharmaceutical salts frequently have enhanced solubility characteristics compared to the compound from which they are derived, and thus are often more amenable to formulation as liquids or emulsions.
Examples of pharmaceutical acid addition salts are the sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, propionate, decanoate, caprylate, acrylate, formate, isobutyrate, caproate, heptanoate, propiolate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, butyne-1,4-dioate, hexyne-1,6-dioate, benzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, phthalate, sulfonate, xylenesulfonate, phenylacetate, phenylpropionate, phenylbutyrate, citrate, lactate, glycollate, tartrate, methanesulfonate, ethanesulfonate, propanesulfonate, naphthalene-1-sulfonate, napththalene-2-sulfonate, mandelate, and the like of a compound of formula I.
Examples of pharmaceutical base addition salts are the ammonium, lithium, potassium, sodium, calcium, magnesiu, methylamino, diethylamino, ethylene diamino, cyclohexylamino, and ethanolamino salts, and the like of a compound of formula I.
The term xe2x80x9csolvatexe2x80x9d represent s an aggregate that comprises one or more molecules of the solute, such as a formula I compound, with one or more molecules of solvent.
The term xe2x80x9csuitable solventxe2x80x9d refers to a solvent which is inert to the ongoing reaction and sufficiently solubilezes the reactants to effect the desired reaction. Examples of suitable solvents include but are not limited to, dichloromethane, chloroform, 1,2-dichloroethane, diethyl ether, acetonitrile, ethyl acetate, 1,3-dimethyl-2-imidazolidinone, tetrahydrofuran, dimethyltormamide, toluene, chlorobenzene, dimethylsulfoxide, mixtures thereof, and the like.
The term xe2x80x9ccarbonyl activating reagentxe2x80x9d refers to a reagent that converts the carbonyl of a carboxylic acid group to one that is more prone to nucleophilic addition and includes, but is not limited to, such reagents as those found in xe2x80x9cThe Peptidesxe2x80x9d, Gross and Meienhofer, Eds., Academic Press (1979), Ch. 2 and M. Bodanszky, xe2x80x9cPrinciples of Peptide Synthesisxe2x80x9d, 2nd Ed., Springer-Verlag Berlin Heidelberg, 1993, hereafter referred to as xe2x80x9cThe Peptidesxe2x80x9d and xe2x80x9cPeptide Synthesisxe2x80x9d respectively. Specifically, carbonyl activating reagents include nucleophilic sources of a halogen such as, thionyl bromide, thionyl chloride, oxalyl chloride, and the like; alcohols such as nitrophenol, pentachlorophenol, and the like; amines such as N-hydroxy-N-methoxyamine and the like; acid halides such as acetic, formic, methanesulfonic, ethanesulfonic, benzenesulfonic, or p-tolylsulfonic acid halide, and the like; and compounds such as 1,1xe2x80x2-carbonyldiimidazole, benzotriazole, imidazole, N-hydroxysuccinimide, dicyclohexylcarbodiimide, and the like.
The term xe2x80x9csuitable thermodynamic basexe2x80x9d refers to a base which acts as a proton trap for any protons which may be produced as a byproduct of the desired reaction or to a base which provides a reversible deprotonation of an acidic substrate and is reactive enough to effect the desired reaction without significantly effecting any undesired reactions. Examples of thermodynamic bases include, but are not limited to, carbonates, bicarbonates, and hydroxides (e.g., lithium, sodium, or potassium carbonate, bicarbonate, or hydroxide), tri-(C1-C4 alkyl)amines, or aromatic nitrogen containing heterocycles (e.g., pyridine).
While all of the compounds of the present invention are useful, certain of the compounds are particularly interesting and are preferred. The following listing sets out several groups of preferred compounds, formulations, and methods. It will be understood that each of the listings may be combined with other listings to create additional groups of preferred embodiments.
a) m is 0 and mxe2x80x2 is 0;
b) m is 0 and mxe2x80x2 is 1;
c) R is at the meta position;
d) R is CHR1NHR2 and R1 is methyl;
e) R is COR3;
f) R is (CH2)COR3;
g) R is (CH2)NR4R5;
h) Rxe2x80x2 is hydrogen;
i) R2 is 4-aminosulfonylbenzyl;
j) R2 is 3,4,5-trimethoxybenzyl;
k) R3 is (3,4,5-trimethoxyphenyl)amino;
l) R3 is (4-aminosulfonylphenyl)amino;
m) R3 (6-methoxyquinolin-8-yl)amino;
n) R4 is hydrogen;
o) R5 5-methylisoxazol-3-oyl;
p) R5 is 3,4,5-trimethoxybenzoyl;
q) R5 3,5-dimethoxy-4-hydroxybenzoyl;
r) R5 is 3,4,5-trimethoxybenzyl;
s) The compound is a pharmaceutical salt;
t) The compound is the hydrochloride;
u) The compounds of the Examples section;
v) The method where the mammal is a human;
w) The method where the oncolytic(s) is selected from: doxorubicin, daunorubicin, epirubicin, vincristine, and etoposide;
x) The method where the neoplasm is of the Wilm""s type, bladder, bone, breast, lung(small-cell), testis, or thyroid or the neoplasm is associated with acute lymphoblastic and myeloblastic leukemia, neuroblastoma, soft tissue sarcoma, Hodgkin""s and non-Hodgkin""s lymphomas, or bronchogenic carcinoma; and
y) The formulation where the oncolytic(s) is selected from the group: doxorubicin, daunorubicin, epirubicin, vincristine, and etoposide.
The compounds of the present invention can be prepared by a variety of procedures, some of which are illustrated in the Schemes below. The particular order of steps required to produce the compounds of formula I is dependent upon the particular compound being synthesized, the starting compound, and the relative lability of the substituted moieties.
Compounds of formula I may be prepared from compounds of formula II as illustrated in Scheme 1 below where R, Rxe2x80x2, and m are as described supra. 
Compounds of formula I may be prepared by dissolving or suspending a compound of formula II in a suitable solvent and adding a suitable thermodynamic base. Typically a preferred and convenient solvent is dimethylformamide. Usually a convenient and preferred thermodynamic base is sodium hydroxide added as a 2N solution in methanol. The reactants are typically combined at room temperature but the resulting solution is typically heated to from about 30xc2x0 C. to about the reflux temperature of the mixture for from 30 minutes to about 18 hours. Preferably, the mixture is heated to at least 50xc2x0 C. for from about 1 to about 6 hours, and is most preferably heated to from about 65xc2x0 C. to about 75xc2x0 C. for from about 1.5 hours to about 3 hours. The base is typically employed in a large molar excess, usually in about a 4 to about an 8 molar excess relative to the compound of formula II. Preferably, about a 5 to about a 7 molar excess is typically employed. Certain intermediates, discussed below, of compounds of formula I may also be prepared by the method discussed above.
Any hydroxy or amino protecting groups found in the cyclized compound of formula I may optionally be removed as taught in Greene to provide the free amino or free hydroxy compounds of formula I. Preferred choices of protecting groups and methods for their removal may be found in the Preparations and Examples sections below.
Compounds of formula I where R is (CH2)mxe2x80x2CHR1NHR2, (CH2)mxe2x80x2CHR1NR4R5, or O(CH2)2NHR2 and R2 is CH2R6 xe2x80x2 may be prepared from compounds of formula I(a), I(c), or I(e) as illustrated in Scheme 2 below where R9 is a carbonyl activating group, and m, mxe2x80x2, Rxe2x80x2, R1, R2, R4, R5, and R6xe2x80x2 are as described supra. 
Compounds of formula I(a), I(c), or I(e) prepared as described in Scheme 1, may be converted to other compounds of the invention For example, the compounds of formula I(a), I(c), and I(d) may be reductively aminated to form the compounds of formula I(b), I(d), and I(f) respectively. Reductive aminations are well known transformations, see, e.g., Larock, xe2x80x9cComprehensive Organic Transformationsxe2x80x9d, pg. 421, VCH Publishers, New York, N.Y., 1989, hereafter referred to as xe2x80x9cLarockxe2x80x9d. In the context of the current invention, the reductive amination may be accomplished via standard solution or combinatorial synthetic techniques.
Compounds of formula III, I(c), or I(e) may be dissolved or suspended in a suitable solvent, optionally in the presence of a suitable thermodynamic base, and a compound of formula I(a) or IV is added to provide an imine intermediate. A Lewis acid catalyst, such as titanium(IV) isopropoxide, may also optionally be employed in order to promote this reaction. Once it is determined that the compound of formula I(a) or IV has been substantially consumed, the imine intermediate is typically reacted in situ with a suitable reducing agent to provide respectively the compounds of formula I(b), I(d), or I(f). The overall conversion may be performed at about 0xc2x0 C. to the boiling point of the mixture but room temperature is a preferred reaction temperature. The individual steps of the formation of the imine and the reduction of the imine to the amine may take from 15 minutes to 24 hours. Imine formation is usually substantially complete in from 15 minutes to an hour while reduction of the imine is usually complete in from 30 minutes to 2 hours. Methanol is typically a preferred solvent.
A thermodynamic base is typically employed when the compound of formula III, I(c), or I(e) is an acid addition salt in order to convert the salt to its free amine form. Preferred thermodynamic bases for this purpose are N-methylmorpholine and triethylamine. A preferred Lewis acid catalyst is titanium(IV) isopropoxide. Suitable reducing agents include, but are not limited to, hydrogen over palladium or platinum on carbon, borane or complexes of borane, e.g., borane-pyridine, borane-t-butylamine, and borane-dimethylamine complex; borohydride reducing agents such as sodium borohydride or sodium cyanoborohydride; and lithium aluminum hydride. Sodium cyanoborohydride is a preferred reducing agent.
The compound of formula III, I(c), or I(e) is typically employed in a slight stoichiometric excess. For example, 1.01 to about 1.5 equivalents, relative to the compound of formula I(a) or IV respectively, is generally employed while 1.05 to about 1.15 equivalents is a preferred amount. The reducing agent is preferably employed in a stoichiometric amount relative to the compound of formula I(a) or IV but a slight excess, from 1.01 to 1.05 equivalents, is acceptable.
Compounds of formula I where R is (CH2)mxe2x80x2CHR1NHR2 or O(CH2)2NHR2R2 is COR6, SO2R7 or a moiety of the formula 
may be prepared from compounds of formula I(c) and I(e) as illustrated in Scheme 3 below where R10 is COR6, SO2R7, or a moiety of the formula 
R11 is O or S, and m, mxe2x80x2, Rxe2x80x2, R1, R6, R6xe2x80x2, R7, and R9 are as described supra. 
Compounds of formula I(c) and I(e) may be converted to other compounds of the invention via standard solution or combinatorial synthetic techniques. For example, a compound of formula I(c) or I(e) dissolved or suspended in a suitable solvent, optionally in the presence of a thermodynamic base, may be treated with a compound of formula IV to provide a compound of formula I(g) or I(h) where R10 is COR6. Typically a preferred and convenient solvent is dichloromethane. When a base is employed, triethylamine is typically a preferred base. Furthermore, when a base is employed, the base and compound of formula IV are typically employed in a slight stoichiometric excess. For example a 1.01 to 1.40 molar excess, relative to the compound of formula I(c) or I(e), is generally employed. About 1.15 to about 1.25 molar excess is typically preferred. When a base is not employed, the compound of formula IV is typically employed in a relatively larger stoichiometric excess. For example, about a 1.5 to about a 3 molar excess, relative to the compound of formula I(c) or I(e), is usually employed. About 1.8 to about 2.2 molar excess is typically preferred. The reaction is usually performed at a temperature range of about 0xc2x0 C. to about the reflux temperature of the solvent for from 10 minutes to 18 hours. Preferably, the reaction is performed at about 15xc2x0 C. to about 40xc2x0 C. for from 5 minutes to about 1 hour.
Under the same conditions as the previous paragraph, a compound of formula I(c) or I(e) may alternatively be treated with a compound of formula V or VI to afford the compounds of formula I where R is (CH2)mxe2x80x2CHR1NHR2 or O(CH2)2NHR2 and R2 is CONHR7, SO2R7 or a moiety of the formula 
Compounds of formula I where R is (CH2)mxe2x80x2COR3 and R3 is C1-C6 alkoxy, an amino ester, or NR4R5 may be prepared from compounds of formula I(i) as illustrated in Scheme 4 below where R12 is NR4 R5, an amino ester, or C1-C6 alkoxy, and m, mxe2x80x2, Rxe2x80x2, R4, R5, and R9 are as described supra 
Compounds of formula I(i), prepared as described in Scheme 1, may also be converted to other compounds of the invention via solution or solid phase synthetic techniques. For example, acids of formula I(i) may be activated to form the activated carboxylic acids of formula VII by methods well known in the chemical arts. See, e.g., The Peptides, Peptide Synthesis and the Examples and Preparations sections below.
Generally, preparation of compounds of formula I(j) where R12 is NR4R5 or an amino ester is performed in a manner similar to the reaction of compounds of formula I(c) or I(e) and IV described in Scheme 3. Specifically, such compounds of formula I(k) may be prepared by dissolving or suspending a compound of formula VII in a suitable solvent, optionally in the presence of a suitable thermodynamic base, and adding an amine of formula III or VIII. Typically a preferred and convenient solvent is dichloromethane. Preferred bases are triethylamine and piperidinylmethylpolystyrene resin. The amine is typically employed in a molar excess. For example, about a 1.5 to about a 3 molar excess, relative to the compound of formula VIII, is usually employed. About 1.8 to about 2.2 molar excess is typically preferred. The reaction is usually performed in a temperature range of about 0xc2x0 C. to about the reflux temperature of the solvent for from 10 minutes to 18 hours. Preferably, the reaction is performed at about 15xc2x0 C. to about 40xc2x0 C. for from 5 minutes to about 2.5 hours.
Alternatively, the compound of formula I(i) may be activated and the addition of a compound of formula III, VIII, or IX may be performed in a one pot process as described in Example 41 below.
The compounds of formula I(j) where R12 is C1-C6 alkoxy may be prepared by methods very well known in the chemical arts. For instruction on the conversion of activated carboxylic acids to esters see, e.g., Larock at 978-979. Alternatively, these compounds of formula I(j) may be prepared directly from the acids of formula I(i) as taught in the Larock reference at pages 966-972 or as disclosed in the Examples section below.
The pharmaceutical salts of the invention are typically formed by reacting a compound of formula I with an equimolar or excess amount of acid or base. The reactants are generally combined in a mutual solvent such as diethylether, tetrahydrofuran, methanol, ethanol, isopropanol, benzene, and the like for acid addition salts, or water, an alcohol or a chlorinated solvent such as dichloromethane for base addition salts. The salts normally precipitate out of solution within about one hour to about ten days and can be isolated by filtration or other conventional methods.
Acids commonly employed to form pharmaceutical acid addition salts are inorganic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, and the like, and organic acids such as p-toluenesulfonic, methanesulfonic acid, ethanesulfonic acid, oxalic acid, p-bromophenylsulfonic acid, carbonic acid, succinic acid, citric acid, tartaric acid, benzoic acid, acetic acid, and the like. Preferred pharmaceutical acid addition salts are those formed with mineral acids such as hydrochloric acid, hydrobromic acid, and sulfuric acid, and those formed with organic acids such as maleic acid, tartaric acid, and methanesulfonic acid.
Bases commonly employed to form pharmaceutical base addition salts are inorganic bases, such as ammonium or alkali or alkaline earth metal hydroxides, carbonates, bicarbonates, and the like. Such bases useful in preparing the salts of this invention thus include sodium hydroxide, potassium hydroxide, ammonium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, calcium hydroxide, calcium carbonate, and the like. The potassium and sodium salt forms are particularly preferred.
It should be recognized that the particular counterion forming a part of any salt of this invention is not of a critical nature, so long as the salt as a whole is pharmacologically acceptable and as long as the counterion does not contribute undesired qualities to the salt as a whole.
The starting materials and compounds of the present invention which are intermediates to other compounds of the present invention may be obtained by a number of routes. For example, compounds of formula II, I(a), I(c), I(e), and I(i) may be prepared according to the route shown in Scheme 5 where R, Rxe2x80x2, and m are as described supra. 
Compounds of formula II may be prepared by dissolving or suspending a compound of formula X in a suitable solvent and adding a compound of formula XI and a suitable thermodynamic base. Dichloromethane is a convenient solvent and is typically preferred. Pyridine is usually the preferred thermodynamic base. This amide forming reaction is also preferably run in the presence of dimethylamino pyridine (DMAP). The compound of formula XI is typically and preferably employed in an eguimolar amount, relative to the compound of formula X, but a slight excess (about a 0.05 to about 0.15 molar excess) is acceptable. The thermodynamic base is typically employed in a slight molar excess. For example, about a 1.01 to about a 1.2 molar excess, relative to the compound of formula X, is typically employed. About a 1.05 to about 1.15 molar excess is generally preferred. The DMAP is employed in a catalytic fashion. For example, about 5 molar percent to about 15 molar percent, relative to the compound of formula X, is typically employed. A 10 molar percent is usually preferred.
Compounds of formula X where R is (CH2)mxe2x80x2COR1, (CH2)mxe2x80x2NHPg, O(CH2)2NHxe2x80x94Pg, or (CH2)mxe2x80x2CO2(C1-C6 alkyl) which are used to prepare compounds of formula I(a), I(c), I(e), and I(i) respectively, are well known in the art and to the extent not commercially available, are readily synthesized by standard procedures commonly employed in the art. For example, these compounds of formula X may be prepared by reduction of the corresponding commercially available nitro compounds. Methods of reducing a nitro group to an amine are well known. See, e.g., Larock at 412-415 or in the Preparations and Examples sections below. In addition, compounds of formula X where R is O(CH2)2NHxe2x80x94Pg may be prepared from commercially available nitrophenols or nitrobenzyl alcohols as described in Preparations 15 and 16 below. Furthermore, the transformations described in Schemes 2-5 may be performed before the cyclization described in Scheme 1 to provide the compounds of formula X with a fully elaborated R substituent.
Compounds of formula III, IV, V, VI, VIII, IX, X, and XI are known in the art and, to the extent not commercially available, are readily synthesized by standard procedures commonly employed in the art.
The optimal time for performing the reactions of Schemes 1-5 can be determined by monitoring the progress of the reaction via conventional chromatographic techniques. Furthermore, it is preferred to conduct the reactions of the invention under an inert atmosphere, such as, for example, argon, or, particularly, nitrogen. Choice of solvent is generally not critical so long as the solvent employed is inert to the ongoing reaction and sufficiently solubilizes the reactants to effect the desired reaction. The compounds of formula II, I(a), I(c), I(e), and I(i) are preferably isolated and purified before their use in subsequent reactions. These compounds may crystallize out of the reaction solution during their formation and then collected by filtration, or the reaction solvent may be removed by extraction, evaporation, or decantation. These intermediates and final products of formula I may be further purified, if desired by common techniques such as recrystallization or chromatography over solid supports such as silica gel or alumina.
The skilled artisan will appreciate that not all substitutents are compatible with all reaction conditions, for example, compounds of the invention where Rxe2x80x2 is hydroxy. These compounds may be protected as the corresponding benzyl ether, and then converted to the hydroxy derivative at a convenient point in the synthesis by hydrogenolysis or other methods well known in the art.
The following Preparations and Examples are provided to better elucidate the practice of the present invention and should not be interpreted in any way as to limit the scope of same. Those skilled in the art will recognize that various modifications may be made while not departing from the spirit and scope of the invention. All publications mentioned in the specification are indicative of the level of those skilled in the art to which this invention pertains. The terms and abbreviations used in the instant Preparations and Examples have their normal meanings unless otherwise designated. For example xe2x80x9cxc2x0 C.xe2x80x9d , xe2x80x9cNxe2x80x9d, xe2x80x9cmmolxe2x80x9d, xe2x80x9cgxe2x80x9d, xe2x80x9cmLxe2x80x9d, xe2x80x9cMxe2x80x9d, xe2x80x9cHPLCxe2x80x9d, xe2x80x9cIRxe2x80x9d, xe2x80x9cMS(FD)xe2x80x9d, xe2x80x9cMS(IS)xe2x80x9d, xe2x80x9cMS(FIA)xe2x80x9d, xe2x80x9cMS(FAB)xe2x80x9d, xe2x80x9cMS(EI)xe2x80x9d, xe2x80x9cUVxe2x80x9d, and xe2x80x9c1H NMRxe2x80x9d, refer to degrees Celsius, normal or normality, millimole or millimoles, gram or grams, milliliter or milliliters, molar or molarity, high performance liquid chromatography, infra red spectrometry, field desorption mass spectrometry, ion spray mass spectrometry, flow injection analysis mass spectrometry, fast atom bombardment mass spectrometry, electron impact mass spectrometry, ultraviolet spectrometry, and proton nuclear magnetic resonance spectrometry respectively. In addition, the absorption maxima listed for the IR spectra are only those of interest and not all of the maxima observed.